Paul Gustard will become defence coach in Eddie Jones' new-look England set-up in time for the RBS 6 Nations campaign.
The former Leicester Tigers flanker will remain with Saracens for the next six weeks before assuming his new role with the Rugby Football Union (RFU).
The RFU confirmed Gustard's appointment on Thursday after completing a smooth set of negotiations with Saracens, easing some of the pressure from the continued wrangling over Steve Borthwick's move to the England set-up from Bristol.
Saracens rugby director Mark McCall has negotiated his wish to keep Gustard on hand at the Aviva Premiership club until mid-January, and that has sealed the 39-year-old's step into the Test arena.
"To be given the chance with England is hugely humbling and I am thrilled to be involved," said Gustard.
"I would like to thank Saracens for allowing me to leave and take up this opportunity. I hope that experience will stand me in good stead for this next challenge.
"This has been a difficult decision to make, but to coach England is an opportunity you just don't turn down. I have enjoyed 10 wonderful years at Saracens, both as a player and as a coach.
"It's been an incredible journey. I have made some amazing memories as part of such a special group, but there is a very exciting opportunity ahead for me that I'm really looking forward to.
"My focus now is the next six weeks by helping this brilliant playing and coaching group prepare for some important games."
New head coach Jones' revamped England coaching set-up continues to take shape, with the former Japan boss keen to have his support staff in place ahead of February's Six Nations kick-off.
Bristol refused to accept assistant coach Borthwick's resignation earlier this week, and continue to seek hefty compensation before sanctioning his switch to the England camp.
Borthwick and Jones teamed up to fine effect with Japan at the World Cup, and the RFU continue to expect the duo will be reunited with England, but Bristol's public remonstrations have significantly delayed that process.
Former Australia boss Jones hailed Gustard's work at Saracens on welcoming him to the England fold.
Gustard founded Saracens' now-famed 'wolf pack' defensive mentality, where hunting and hounding opponents into costly errors proved an attacking weapon all of its own.
Now the former Saracens and London Irish back-rower has the chance to transfer that relentless acumen into the international game.
"An important part of England going forward is to make sure we keep the traditional and fundamental bits of English rugby in place and that has always been a strong set piece and a very aggressive defence," said Jones.
"He has overseen Saracens growth as a team. He has produced an aggressive defence system there and we are hoping he can do the same for England."